Changes in structure and floristic diversity from 2002 to 2008 in Montane Mixed Rain Forest in central southern region of Paraná State, Brazil

Abstract

The changes in the successional structure and floristic diversity of a fragment of Mixed Rain Forest, located on Irati National Forest, Parana State, were monitored over six years. Data were collected in an area of 25 ha, measured in 2002, 2005 and 2008 and on the three occasions, all trees with DBH ≥ 10 cm were measured, numbered and identified. To study the successional structure the trees were classified into four ecophysiological groups: a) pioneer; b) early secondary; c) late secondary and d) no characterization. The floristic diversity was evaluated using the Shannon (H'), Simpson (D’) and Pielou’s Evenness (J') indices. The analyses showed increase from 89 to 90% in the number of individuals belonging to the category of secondary species, as well as an increase of 4.46% in the number of species and genera of 3.80%, indicating that the forest is more diverse (richness) and structured. The main factor for this result is the advanced stage of succession which favor the emergence of new species and helps to reduce the number of individuals of dominant species as corroborated by the values of the indices of Shannon (H’=3.55 and 3.57), Simpson (D`=0.044 and 0.043) and Pielou’s Evenness (J'=75%) during the period.